Field
Embodiments of the invention relate to designs of a microfabricated beam scanning device and its use in an arrayed format.
Background
Beam steering in imaging devices can be realized using various techniques making use of electro or thermo optical effects on chip or using mechanical scanning by moving lenses or mirrors in free space. A typical mechanism for beam steering uses a mirror for steering the light coming out of an optical waveguide and includes a collimating lens and a mirror located at some distance from the waveguide. The two-dimensional scanning mirror deflects the light beam and projects it over a sample.
The light propagation along optical waveguides patterned on chip occurs in-plane. However planar technologies commonly used for fabrication of integrated devices do not allow for fabrication of efficient collimating (or focusing) elements to obtain high quality performance. The lens is commonly located symmetrically with respect to the optical axis of the waveguide. A hybrid solution is often used to overcome this issue: a free space lens is attached to the same optical bench where the waveguide is fixed. However, aligning the free space lens requires very high precision in all three orthogonal directions on the order of 1 micron.
Many interferometry devices, such as optical coherence tomography (OCT) systems, use collimated light that is further directed to a focusing lens operated in telecentric mode to make the total optical path length indifferent to beam location on the imaged sample. Using free space optical elements can provide high quality performance; however it is relatively bulky, requires precise alignment, and does not leave much possibility for reduction of the overall size of the device.